Concentration apparatus for quantitative analysis of a substance in a liquid



July 23, 1963 A. FERRARI 3,093,718

CONCENTRATION APPARATUS FOR QUANTITATIVE ANALYSIS OF A SUBSTANCE IN ALIQUID Filed Sept. 8, 1959 IN V EN TOR A voges FE A Arr-owns) ratesatent Ofificc Patented July 23, 1963 CONCENTRATION APPARATUS FORQUANTITA- TIVE ANALYSES OF A SUBSTANCE IN A LIQUID Andres Ferrari,Scarsdale, N.Y., assignor to Technicon Instruments Corporation,Chauncey, N.Y., a corporation of New York Filed Sept. 8, 1959, Scr. No.838,579 6 Claims. (Cl. 23-253) This invention relates to a liquidconcentration and treatment method and apparatus. for quantitativeanalysis of said liquid in respect to a substance therein.

One object of the invention is to provide apparatus which is welladapted for use in a continuou analysis system for flash-heating aflowing stream of a liquid for partial evaporation thereof, in order toincrease the concentration of a substance therein, especially in thecase of liquids in which the substance is present in minute or onlytrace quantities, with concurrent with-dr-awalof the concentrated liquidand treatment thereof for colorimetric examination.

In accordance with another object of the invention, the apparatus may beprovided with means to introduce a reagent into the liquid underinvestigation with respect to a constituent thereof whereby when theliquid containing said reagent is heated, the constituent which may bepresent in a normally insoluble form is. rendered soluble in the liquidand its concentration therein is increased by liquid evaporation. Forexample, in theanalysis of boiler feed water supplied to steam boilersfrom condensers in power plants or boiler rooms, such water containing,in addition to water-soluble iron, highly oxidized iron which isconsidered insoluble, would be rendered totally soluble by the additionof sulfuric acid to said liquid andthe heating of the liquid wouldgreatly increase the concentration of the iron whereby to facilitateanalysis.

A further object is the provision of a continuous analysis system ormethod, as distinguished from a batch or discontinuous method ofanalysis, for performing quantitative analyses of a liquid in respect tosubstances which are present therein in trace or very small quantities.

The above and other objects, features and advantages of this inventionwill be fully understood from the following description considered inconnection with the accompanying illustrative drawings.

In the drawings:

FIG. 1 is a schematic view illustrative of the apparatus and method ofthe present invention;

FIG. 2 is a view partly in elevation and partly in section and on alarger scale of part of the apparatus; and

FIG. 3 is. a sectional view, on a larger scale, on the line 3-3 of FIG.2.

Referring to the drawings in detail, the apparatus of the presentinvention comprises a glass flask 1t mounted for rotation about itslongitudinalaxis and disposed in a downwardly inclined position forrotation in said position with an electrically heated oven 12. Asillustrated in FIG. 2, oven 12 has a stationary lower section 14 and anupper movable section 16 which is hinged to the lower section 14 by thehinge indicated at 18 so that said upper section can be moved toretracted position to permitthe insertion and removal of flask 10. Theelectric resistance heating elements on said sections are indicated at20, and it will be understood that the electric heater constituted bysaid resistance elements surrounds the flask and also confronts thebottom thereof as illustrated in FIG. 2. Sections 14 and 16 of theelectrically heated oven 12 are provided with suitable heat insulationas indicated at 22.

The flask lit is mounted for rotation by a hollow rotary shaft 24 whichhas an end portion 26 which is firictionally engaged by the mouth 28 ofthe flask, interiorly of the latter, for removably supporting the flaskand providing a fluid-tight seal with the mouth of the flask. Hollowshaft 24 is removably secured by-a chuck St) to the flange 31 of arotary gear 32 which is journaled in a bearing 33 at the upper end ofpost 34. An electric motor 35 which may also be supported on said posta-ctu-ates shaft 24, the driving connection between the motor and saidshaft being here shown as comprising the bevel gear 36 which meshes withthe bevel gear 32. It will be understood that flask 10 may be rotated ata suitable speed, according to the gear ratio of gears 32 and 36 andalso by the provision, ifdesired, of speed reducing gearing (not shown),drivingly connecting the shaft of motor 35 to shaft 24 in any suitableway.

A plurality of fluid passages extend through shaft 24 into flask 10These passages are preferably constituted by a plurality of glass tubes38, 40 and 42. Tube 38 provides a tubular passage for the introductionof the liquid, which is to be concentrated, into the flask at an upperpart thereof, as clearly shown in FIGS. 1 and 2. More particularly, theliquid inlet for the flask is provided by the inner end or outlet end 44of said tube, so that the liquid supplied through tube 38 flowsdownwardly on the inner side of the flask to the bottom thereof. Sincethe flask is being rotated and is in heated condition while the liquidis introduced into the flask, the liquid comes in contact withsuccessive portions of the flask peripherally thereof, as well aslongitudinally thereof in the form of a film-like coating on the innersurface of the flask so that rapid evaporation of some of the liquidoccurs with concomitant concentration of the liquid during the flow ofthe liquid to the bottom of the flask. Tube 40 provides means forwithdrawing the concentrated liquid from the flask and for this purposethe inner end portion 46 of said tube is positioned, as illustrated inFIG. 2, so that it is immersed in the pool of liquid which collects atthe bottom of the flask. Tube 42 is provided for withdrawing vapors orfumes from theflask'formed as a result of theheating or flashevaporation of some of the liquid which is admitted through tube 38.Tube 42 is connected to an aspirator 43 of a well known type which isoperated by a stream of water, which flows through tube 45, forwithdrawing the fumes through said tube. The water is also effective todilute and cool the fumes so that the fluids may be exhausted to wastethrough the outlet 47. The rate of withdrawal of the vapors or fumes maybe adjusted to prevent the accumulation of excessive pressure within theflask.

The apparatus of the present invention includes means for transmittingthe liquid through tube 38 for concentration in flask 10, as Well asmeans for withdrawing from the flask the concentrated liquid,concurrently with the introduction into the flask of the liquid which isto be concentrated therein. For these purposes there is provided aproportioning pump 52 of any suitable construction for transmittingliquids or fluids into the flask and withdrawing them from the flask atpredetermined rates of flow. The proportioning pump is preferably of thetype described in U.S. Patent No. 2,893,324, issued to the assignee ofthe present application. Briefly described, said pump comprises aplurality of resiliently compressible tubes which are mounted on aplaten in laterally spaced relation and which are engaged simultaneouslyby a plurality of pressure rollers which are moved progressively alongthe lengths of the tubes for pumping the liquids or fluids therethrough.As the pnoportioning pump does not'in itself constitute a part of thepresent invention, further description and illustration thereof areunnecessary.

The apparatus of the present invention, as thus far described, may beemploved solely for the purpose of concentrating a liquid, for example,when the liquid contains a very small quantity of a substance by reasonof which quantitative analysis of the liquid in respect to saidsubstance in the liquid is ordinarily extremely difl'icult orimpossible, especially in continuous analysis or monitoring systems.More particularly, in power plant operations, for example, the analysisof boiler feed water in respect to the iron or copper content thereof,requires the employment of trace analysis techniques, such as the use oflong flow cell colorimeters and other complicated devices and proceduresbecause of the low concentration of iron or copper, as the case may be,in the feed water. Accordingly, by treating the boiler feed water fiorincreasing the concentration of the iron or copper concurrently with theperformance of the analysis or monitoring operation, the importantadvantage is obtained by reason of the fact that it is possible toemploy a continuous analysis system without requiring the use ofcomplicated trace analysis techniques and devices. This will be moreclearly evident from the following description of a method of continuousanalysis of boiler feed water for the quantitative determination of irontherein.

With further reference to FIG. 1, a stream of the boiler feed water istransmitted by the pump tube 54 to a helical glass mixing coil 56simultaneously with the transmission to said mixing coil of sulfuricacid (50% concentration) by the pump tube 58. When the water containingthe sulfuric acid is heated to a high temperature in flask any ironwhich may be present in the water and is normally insoluble therein isrendered soluble. The acid treated water passes from the mixing coil 56to the tube 38 and is introduced by the latter into the heated revolvingflask, and as a result any insoluble iron present in the water isdissolved therein and the total iron concentration is increased. Theconcentrated liquid is withdrawn through the flask 10' through the tube40 and is transmitted through the mixing and cooling coil 60 by the pumptube 62 where it is mixed with potassium thiocy-anate (40%concentration) introduced into the mixing coil by the pump tube 64. Airor other inert gas is preferably introduced into the liquid stream priorto the flow thereof into the mixing coil, through the pump tube 66,whereby the stream of liquid is divided by said air or other inert gasinto flowing segments of liquid separated from each other by interveningsegments of the gas, one of the purposes of segmentizing the streambeing to provide a cleansing action on the tubular pas sages. The pumptube 62 by which the liquid stream is withdrawn from flask 10 andtransmitted through the mixing coil together with the potassiumthi-ocyanate is connected to a tube 68 for transmitting the liquidthrough the flow cell (not shown) of a colorimeter 7 0 which controlsthe operation of a recorder 72 in a well known manner. It will beunderstood that the potassium thiocyanite constitutes a color reagentfor treating the concentrated liquid stream for colorimetric examinationin respect to the total iron content of the boiler feed waterconcurrently with the concentration operation.

An overflow tube 74, which is made of glass, is provided to limit thequantity of liquid which may collect in flask 10, the inlet end 76 ofthis overflow tube being above the inlet end of tube 46. Said overflowtube 74 is connected to the aspirator 43 for the removal of excessliquid from the flask, and it will be noted that the stream of waterwhich flows through the aspirator is effective to cool and dilute thehot liquid.

As an illustrative but not limitative example of the rates of flow ofthe above-mentioned fluids pursuant to the operation of theproportioning pump 52 concurrently with the continuous concentrationdescribed above, it may be noted that the boiler feed water underanalysis is transmitted by pump tube 54 at the rate of 11.7 mls. perminute, the sulfuric acid is transmitted through pump tube 58 at therate of 1.2 mls. per minute, the potassium thiocyanate is transmittedthrough pump tube 64 at the rate of 2.0 mls. per minute, and the air istransmitted through pump tube 66 at the rate of 0.8 ml. per minute. Theliquid introduced into the flask is heated to a temperature of about 350C. to 400 C.

While I have shown and described the preferred embodiment of myinvention, it will be understood that the invention may be embodiedotherwise than as herein specifically illustrated or described, and thatcertain changes in the form and arrangement of par-ts and in thespecific manner of practicing the invention may be made withoutdeparting from the underlying idea orprinciples of this invention withinthe scope of the appended claims.

What I claim is:

l. Liquid-treatment apparatus, comprising a flask mounted for rotationabout its longitudinal axis, said flask being disposed in a downwardlyinclined position during its rotation, means =for rotating said flask insaid position about said axis, means for heating said flask during saidrotation thereof, and stationary conduit means extending into said flaskand providing a plurality of fluid passages in communication with theinterior of the flask, said flask being rotated about said conduit meansby said flask rotating means, one of said passages terminating in aliquid inlet positioned above the bottom of the flask adjacent the sidethereof so that liquid admitted through said inlet flows down and aroundon the inner heated side of the flask during the rotation of said flaskin contact with successive peripheral portions or said inner side toform a liquid film thereon for effecting a rapid heating and partialevaporation of the liquid as it flows to the bottom of the flask,another of said passages terminating nearer the bottom of the flask thansaid inlet passage and constituting an outlet passage for the heatedliquid while the flask rotates, and another of said passages having aninlet opening above the termination of said last mentioned passage andproviding an overflow passage for the heated liquid to limit thequantity of concentrated liquid at the bottom of the flask while theflask rotates. e a

2. Liquidatreatment apparatus, comprising a flask mounted for rotationabout its longitudinal axis, said,

flask being disposed in a downwardly inclined position during itsrotation, means for rotating said flask in said position about saidaxis, means for heating said flask during said rotation thereof, aid aplurality of stationary conduits extending into said flask for providinga plurality cf fluid passages in communication with the interior of theflask, said flask being rotated about said conduit means by said flaskrotating means, one of said passages terminating in a liquid inletpositioned above the bottom of the flask adjacent the side thereof sothat liquid admitted through said inlet flows down and around on theinner heated side of the flask during the rotation of said flask incontact with successive peripheral portions of said inner side to form aliquid filmrthereon for effecting a rapid heating and partialevaporation of the liquid as it flows to the bottom of the flask,another of said p'a-ssages terminating nearer the bottom of the flaskthan said inlet passage and constituting an outlet pass-age for theheated liquid which the flask rotates, another of said passages havingan inlet opening above the lower end of said last mentioned passage andproviding an overflow passage for the heated liquid to limit thequantity of heated liquid at the bottom of the flask, one of saidconduits providing a passage for withdrawing from said flask vaporsformed during said heating of the liquid.

3. Liquidtreatment apparatus, comprisifig a flask having an open top, aninclined rotary hollow member inserted in said open top and engagedtherewith for mounting said flask for rotation about its longitudinalaxis in a downwardly inclined position, means for rotating said hollowmember and thereby rotating said flask in said position about said axis,means for heating said flask during said rotation thereof, and aplurality of stationary conduits disposed in said rotary hollow memberand extending into said flask through said open top thereof to provide aplurality of stationary fluid passages in communication with theinterior f said flask during the rotation thereof, one of said conduitsterminating in a liquid inlet positioned above the bottom of said flaskadjacent the side thereof so that liquid admitted through said inletduring the rotation of said flask flows down and around on the innerheated side of the flask during the rotation of said flask in contactwith successive peripheral portions of said inner side thereof foreffecting a rapid heating and partial evaporation of the liquid as itflows to the bottom of the flask, and another of said conduitsterminating nearer the bottom of said flask than said liquid inlet andconstituting an outlet passage for the heated liquid.

4. Liquid-treatment apparatus, comprising a flask having an open top, aninclined rotary hollow member inserted in said open top and engagedtherewith for mounting said flask for rotation about its longitudinalaxis in a downwardly inclined position, means for rotating said hollowmember and thereby rotating said flask in said position about said axis,means for heating said flask during said rotation thereof, and aplurality of stationary conduits disposed in said rotary hollow memberand extending into said. flask through said open end thereof to provide-a plurality of stationary fluid passages in communication with theinterior of said flask while the flask rotates, one of said conduitsterminating in a liquid inlet positioned above the bottom of said flaskadjacent the side thereof so that liquid admitted through said inletflows down and around on the inner heated side of the flask during therotation of said flask in contact with successive peripheral portions ofsaid inner side thereof for effecting a rapid heating and partialevaporation of the liquid as it flows to the bottom of the flask,another of said conduits terminating nearer the bottom of said flaskthan said liquid inlet and constituting an outlet passage for the heatedliquid, and another of said conduits having an inlet opening above thelower end of said last mentioned conduit for providing an overflowpassage for the heated liquid to limit the quantity of liquid in saidflask.

5. Apparatus for treating a liquid for quantitative analysis in respectto a substance present therein in a small quantity, comprising a vesselmounted for rotation about its longitudinal axis and having a downwardlyinclined inner surface means for rotating said vessel about said axis,means for heating said vessel while it is being rotated about said axis,an inlet tube for said liquid having its outlet end positioned above thebottom of said vessel adjacent said inner turfaceso that liquid admittedthrough said inlet end flows down and 'around said inner surface duringthe rotation of said vessel to form a liquid film thereon for effectinga rapid evaporation of a portion of said liquid as it flows to thebottom of said vessel, an outlet tube having its inlet end adjacent thebottom of said vessel [for withdrawing the heated liquid therefrom inthe form of a stream, said tubes being stationary and said vessel beingrotated around the axes of said tubes by said rotating means while theflask is being heated and means in liquid flow communication with saidoutlet tube for treating said withdrawn liquid stream for analysisconcurrently with said evaporation operation and rotation of saidvessel.

6. Apparatus for treating a liquid for quantitative analysis in respectto a substance present therein in a small quantity, comprising a vesselmounted for rotation about its longitudinal axis and having a downwardlyinclined inner surface means for rotating said vessel about said axis,means for heating said vessel during its said rotation and therebyheating said inner surface, an inlet tube for said liquid having itsoutlet end positioned above the bottom of said vessel adjacent saidinner surface so that liquid admitted through said inlet end flows downand around said heated inner surface during the rotation of said vesselto form -a liquid film thereon for effecting a rapid heating and partialevaporation of the liquid as it flow-s to the bottom of said vessel, anoutlet tube having its inlet end adjacent the bottom of said vessel forwithdrawing the concentrated liquid therefrom in the form of a stream,said tubes being stationary and said vessel being rotated around theaxes of said tubes by said rotating means while the flask is beingheated, means in liquid flow communication with said outlet tube fortreating said withdrawn liquid stream for analysis concurrently withsaid evaporation operation and rotation of said vessel, and a stationarytube extending into said vessel to a point above end of said outlet tubefor Withdrawing vapors formed during the heating of said vessel.

References Cited in the file of this patent UNITED STATES PATENTS1,086,432 Zinkeiser et a1. July 14, 1911 1,231,247 Freeman June 26, 19172,686,754 Monod Aug. 17, 1954 2,879,141 Skeggs Mar. 24, 1959 2,899,280Whitehead Aug. 11, 1959 2,941,501 Bell June 21, 1960 OTHER REFERENCESAnalytical Chemistry, volume 14, Feb. 15, 1942, page 166, Determinationof Solubilities of Gases at High Temperatures and High Pressures by theRotating Born by Ispatieff et a1.

5. APPARATUS FOR TREATING A LIQUID FOR QUANTITATIVE ANALYSIS IN RESPECTTO A SUBSTANCE PRESENT THEREIN IN A SMALL QUANTITY, COMPRISING A VESSELMOUNTED FOR ROTATION ABOUT ITS LONGITUDINAL AXIS AND HAVING A DOWNWARDLYINCLINED INNER SURFACE MEANS FOR ROTATION SAID VESSEL ABOUT SAID AXIS,MEANS FOR HEATING SAID VESSEL WHILE IT IS BEING ROTATED ABOUT SaID AXID,AN INLET TUBE FOR SAID LIQUID HAVING ITS OUTLET END POSITIONED ABOVE THEBOTTOM OF SAID VESSEL ADJACENT SAID INNER TURFACE SO THE LIQUID ADMITTEDTHROUGH SAID INLET END FLOWS DOWN AND AROUND SAID INNER SURFACE DURINGTHE ROTATION OF SAID VESSEL TO FORM A LIQUID FILM THEREON FOR EFFECTINGA RAPID EVAPORATION OF A PORTION OF SAID LIQUID AS IT FLOWS TO THEBOTTOM OF SAID VESSEL, AN OUTLET TUBE HAVING ITS INLET END ADJACENT THEBOTTOM OF SAID VESSEL FOR WITHDRAWING THE HEATED LIQUID THEREFROM IN THEFORM OF A STREAM, SAID TUBES BEING STATIONARY AND SAID VESSEL BEINGROTATED AROUND THE AXES OF SAID TUBES BY SAID ROTATING MEANS WHILE THEFLASK IS BEING HEATED AND MEANS IN LIQUID FLOW COMMUNICATION WITH SAIDOUTLET TUBE FOR TREATING SAID WITHDRAWN LIQUID STREAM FOR ANALYSISCONCURRENTLY WITH SAID EVAPORATION OPERATION AND ROTAION SAID VESSEL.